1. Technical Field
The present invention relates to a vehicle occupant protection apparatus. In particular, the present invention relates to an air bag that includes a tether for controlling the direction and amount of inflation of the air bag.
2. Description of Related Art
It is known to provide an air bag with an internal tether. The tether is connected between two portions of the air bag. When the air bag inflates to a first volume, the tether limits or controls relative movement of the two portions the air bag. This helps to control the movement of the air bag portions and thus helps to control the direction and amount of inflation of the air bag.
German Gebrauchsmuster DE 298 19 999 U1 discloses an air bag having two panels joined by a seam that includes a slack thread. When the air bag inflates, the thread extends between the panels and acts as a tether.
The present invention is an inflatable vehicle occupant protection device for helping to protect an occupant of a vehicle. The device is inflatable from a deflated condition to an inflated condition by inflation fluid from an inflation fluid source. The device comprises flexible material defining an inflation fluid volume for receiving inflation fluid, including a first panel portion and a second panel portion. The first panel portion has a plurality of discrete openings, and the second panel portion also has a plurality of discrete openings. The first panel portion overlies the second panel portion when the device is in the deflated condition. A tether interconnects the first panel portion and the second panel portion. The tether includes a single thread extending through the plurality of openings in the first panel portion and through the plurality of openings in the second panel portion in a serpentine manner. The single thread has loop thread portions located outside the inflation fluid volume.
The first panel portion is spaced apart from the second panel portion when the device is in the inflated condition with the tether extending between the first and second panel portions to limit movement of the first panel portion away from the second panel portion. The panel portions move relative to the single thread as the device is inflated from the deflated condition to the inflated condition.
In a preferred embodiment, the tether includes a first stop member on the first end portion of the tether and a second stop member on the second end portion of the tether for blocking movement of the end portions of the tether through the openings in the portions upon movement of the first panel portion away from the second panel portion.